JPH02312316A - High frequency oscillation type proximity switch - Google Patents
High frequency oscillation type proximity switchInfo
- Publication number
- JPH02312316A JPH02312316A JP1134234A JP13423489A JPH02312316A JP H02312316 A JPH02312316 A JP H02312316A JP 1134234 A JP1134234 A JP 1134234A JP 13423489 A JP13423489 A JP 13423489A JP H02312316 A JPH02312316 A JP H02312316A
- Authority
- JP
- Japan
- Prior art keywords
- oscillation
- circuit
- frequency
- amplitude
- proximity switch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000010355 oscillation Effects 0.000 title claims abstract description 96
- 239000007769 metal material Substances 0.000 claims abstract description 3
- 239000000696 magnetic material Substances 0.000 claims description 24
- 230000007423 decrease Effects 0.000 claims description 18
- 239000000126 substance Substances 0.000 claims 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 40
- 229910052782 aluminium Inorganic materials 0.000 abstract description 26
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 26
- 229910052742 iron Inorganic materials 0.000 abstract description 20
- 230000035945 sensitivity Effects 0.000 abstract description 8
- 239000000463 material Substances 0.000 abstract description 6
- 239000004411 aluminium Substances 0.000 abstract 3
- 238000001514 detection method Methods 0.000 description 26
- 238000013459 approach Methods 0.000 description 16
- 238000010586 diagram Methods 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/10—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils
- G01V3/101—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil
- G01V3/102—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil by measuring amplitude
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/945—Proximity switches
- H03K17/95—Proximity switches using a magnetic detector
- H03K17/9505—Constructional details
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/945—Proximity switches
- H03K17/95—Proximity switches using a magnetic detector
- H03K17/952—Proximity switches using a magnetic detector using inductive coils
- H03K17/9537—Proximity switches using a magnetic detector using inductive coils in a resonant circuit
- H03K17/954—Proximity switches using a magnetic detector using inductive coils in a resonant circuit controlled by an oscillatory signal
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
- H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
- H03K2217/945—Proximity switches
- H03K2217/95—Proximity switches using a magnetic detector
- H03K2217/952—Detection of ferromagnetic and non-magnetic conductive targets
Abstract
Description
【発明の詳細な説明】
〔発明の分野〕
本発明は高周波発振型近接スイッチに関し、特に非磁性
体の金属体等を検出できるようにした高周波発振型の近
接スイッチに関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a high frequency oscillation type proximity switch, and more particularly to a high frequency oscillation type proximity switch capable of detecting non-magnetic metal objects.
一般に高周波発振型近接スイッチは、例えば第８図に示
すように検出コイルＬとコンデンサＣによって並列共振
回路１が構成され、この並列共振回路１に発振回路２が
接続されて共振周波数の高周波を発振させており、その
発振信号を検波回路３によって検波している。そして検
出コイルＬの近傍に金属体４が接近すれば検出コイルＬ
の損失が増加し発振状態が変化するためその振幅値も低
下する。従って検波回路３の出力を比較回路５に与え所
定レベルで弁別して物体検知信号を得て出力回路６より
外部に与えるようにしている。こうすれば発振回路２の
振幅値の低下に基づいて物体の近接を検出することがで
きる。Generally, in a high-frequency oscillation type proximity switch, a parallel resonant circuit 1 is configured by a detection coil L and a capacitor C, as shown in FIG. The oscillation signal is detected by the detection circuit 3. If the metal body 4 approaches the detection coil L, the detection coil L
As the loss increases and the oscillation state changes, its amplitude value also decreases. Therefore, the output of the detection circuit 3 is applied to the comparison circuit 5 and discriminated at a predetermined level to obtain an object detection signal, which is then applied to the outside from the output circuit 6. In this way, the proximity of an object can be detected based on the decrease in the amplitude value of the oscillation circuit 2.
従来の高周波発振型近接スイッチでは、金属体、特に磁
性体である鉄製の部材の接近により検出コイルの損失が
大きくなるので磁性体に対する感度が高くなっている。In conventional high-frequency oscillation type proximity switches, the loss of the detection coil increases due to the proximity of a metal body, particularly a magnetic iron member, so the sensitivity to magnetic bodies is high.
このような従来の高周波発振型近接スイッチでは、非磁
性材料例えばアルミニウム等の部材を検″知することが
できない、近年種々の設備の軽量化に伴い工場等の加工
対象（ワーク）として軽いアルミニウム材料が多く使用
されるようになり、これらの材質の物体を検出する必要
が高まっている。Conventional high-frequency oscillation type proximity switches cannot detect non-magnetic materials such as aluminum.In recent years, as various types of equipment have become lighter, lightweight aluminum materials have been used as processing objects (workpieces) in factories. are increasingly used, and there is an increasing need to detect objects made of these materials.
しかし鉄製の物体が検出コイルに接近したときには検出
コイルの損失が増加するように変化し、アルミニウムの
物体が近接したときには検出コイルのサセプタンスが増
加することとなる。従ってアルミニウムが接近しても検
出コイルに与える損失分が小さいため、振幅変化が小さ
く検出感度が低いという欠点があった。However, when a steel object approaches the detection coil, the loss of the detection coil increases, and when an aluminum object approaches, the susceptance of the detection coil increases. Therefore, even if aluminum approaches, the loss imparted to the detection coil is small, so there is a drawback that the amplitude change is small and the detection sensitivity is low.
本願の請求項１の発明はこのような従来の高周波発振型
近接スイッチの問題点に鑑みてなされたものであって、
鉄等の磁性体とアルミニウム等の非磁性体とを同一の感
度で検出できるようにすることを技術的課題とする。The invention of claim 1 of the present application was made in view of the problems of the conventional high frequency oscillation type proximity switch,
The technical challenge is to be able to detect magnetic materials such as iron and non-magnetic materials such as aluminum with the same sensitivity.
又本願の請求項２の発明はアルミニウム材料等の非磁性
体にのみ感度を有する高周波発振型近接スイッチを提供
することを技術的課題とする。The technical object of the invention of claim 2 of the present application is to provide a high frequency oscillation type proximity switch that is sensitive only to non-magnetic materials such as aluminum materials.
又本願の請求項３の発明は鉄等の磁性体にのみ感度を有
する高周波発振型近接スイッチを提供することを技術的
課題とする。Further, the technical object of the invention according to claim 3 of the present application is to provide a high frequency oscillation type proximity switch that is sensitive only to magnetic materials such as iron.
本願の請求項１の発明は発振周波数ｆ０で発振する発振
回路と、発振回路の正帰還ループ間に接続され発振周波
数よりわずかに高い共振周波数ｔｚ （ｆｏ＜ｆｇ）を
有するタンク回路と、発振回路の振幅を所定の閾値レベ
ルで弁別する比較回路と、を有し、磁性体及び非磁性体
金属体が同一位置に近接したとき同一の発振レベルが低
下する発振周波数に設定したことを特徴とするものであ
る。The invention of claim 1 of the present application includes an oscillation circuit that oscillates at an oscillation frequency f0, a tank circuit connected between the positive feedback loop of the oscillation circuit and having a resonant frequency tz (fo<fg) slightly higher than the oscillation frequency, and an oscillation circuit. and a comparison circuit that discriminates the amplitude of the oscillation at a predetermined threshold level, and is characterized in that the oscillation frequency is set to such that the same oscillation level decreases when the magnetic material and the non-magnetic metal material are close to the same position. It is something.
又本願の請求項２の発明は発振周波数ｆ０で発振する発
振回路と、発振回路の正帰還ループ間に接続され発振周
波数よりわずかに低い共振周波数ｆ。Further, the invention according to claim 2 of the present application is an oscillation circuit that oscillates at an oscillation frequency f0, and a resonant frequency f slightly lower than the oscillation frequency, which is connected between the positive feedback loop of the oscillation circuit.
（ｆｇ＞ｆｓ）を有するタンク回路と、発振回路の振幅
を所定の閾値レベルで弁別する比較回路と、を有し、比
較回路は非磁性体の近接による発振振幅の上昇に基づい
て非磁性体のみを検出するものであることを特徴とする
ものである。(fg>fs), and a comparison circuit that discriminates the amplitude of the oscillation circuit at a predetermined threshold level. This feature is characterized in that it detects only
更に本願の請求項３の発明は発振周波数ｆ、で発振する
発振回路と、発振回路の正帰還ループ間に接続され発振
周波数よりわずかに低い共振周波数・ｆｓ （ｆｇ＞ｆ
ｓ）を有するタンク回路と、発振回路の振幅を所定の閾
値レベルで弁別する比較回路と、を有し、比較回路は磁
性体の近接による発振振幅の低下に基づいて磁性体のみ
を検出するものであることを特徴とするものである。Furthermore, the invention of claim 3 of the present application provides an oscillation circuit that oscillates at an oscillation frequency f, and a positive feedback loop of the oscillation circuit that is connected to a resonant frequency fs (fg>f) that is slightly lower than the oscillation frequency.
s), and a comparison circuit that discriminates the amplitude of the oscillation circuit at a predetermined threshold level, and the comparison circuit detects only the magnetic material based on a decrease in the oscillation amplitude due to the proximity of the magnetic material. It is characterized by:
このような特徴を有する本願の請求項１の発明によれば
、発振回路の正帰還ループに発振周波数よりわずかに高
い共振周波数を持つタンク回路を接続して近接スイッチ
が構成されている。この近接スイッチにアルミニウム等
の非磁性体の物体が近接したときにはタンク回路の共振
周波数が高い周波数側に変化して正帰還量が小さくなり
発振振幅が低下する。同様にして鉄製等の磁性体の部材
が近接したときにはタンク回路のコイルの損失分が増加
するため発振出力が低下する。従って発振回路の発振周
波数を適当な値に設定しておくことにより鉄とアルミニ
ウムの近接時に同一の振幅レベルの低下となるように設
定することができる。According to the invention of claim 1 of the present application having such features, a proximity switch is constructed by connecting a tank circuit having a resonant frequency slightly higher than the oscillation frequency to the positive feedback loop of the oscillation circuit. When a non-magnetic object such as aluminum comes close to this proximity switch, the resonance frequency of the tank circuit changes to a higher frequency side, the amount of positive feedback becomes smaller, and the oscillation amplitude decreases. Similarly, when a magnetic member made of iron or the like comes close to each other, the loss of the coil of the tank circuit increases, and the oscillation output decreases. Therefore, by setting the oscillation frequency of the oscillation circuit to an appropriate value, it is possible to set the oscillation frequency so that the same amplitude level decreases when iron and aluminum come close to each other.
又本願の請求項２の発明によれば、正帰還ループの共振
周波数を発振周波数よりわずかに低い周波数としている
。このときアルミニウム等の非磁性体が接近すればタン
ク回路の共振周波数が上昇するため発振が開始され、又
は発振の振幅が上昇する。又鉄等の磁性体が近接すれば
発振回路は発振せず又は振幅レベルが低下するため、非
磁性体のみを弁別して検知するようにしている。According to the invention of claim 2 of the present application, the resonant frequency of the positive feedback loop is set to be slightly lower than the oscillation frequency. At this time, if a non-magnetic material such as aluminum approaches, the resonant frequency of the tank circuit increases, so oscillation starts or the amplitude of oscillation increases. Furthermore, if a magnetic material such as iron comes close, the oscillation circuit will not oscillate or the amplitude level will drop, so only non-magnetic material is discriminated and detected.
又本願の請求項３の発明においても正帰還ループの共振
周波数を発振周波数よりわずかに低い周波数としている
。このとき鉄等の磁性体が接近すれば振幅レベルが低下
するため磁性体のみを弁別して検出するようにしている
。Also, in the invention of claim 3 of the present application, the resonant frequency of the positive feedback loop is set to be slightly lower than the oscillation frequency. At this time, if a magnetic material such as iron approaches, the amplitude level will drop, so only the magnetic material is discriminated and detected.
そのため本願の請求項１の発明によれば、鉄やアルミニ
ウム等の材質にかかわらず金属物に対して同一の感度低
下が得られるため、この振幅レベルの低下に基づいて物
品を検出することができる。Therefore, according to the invention of claim 1 of the present application, the same sensitivity reduction can be obtained for metal objects regardless of the material, such as iron or aluminum, so that the object can be detected based on this reduction in the amplitude level. .
又本願の請求項２の発明では、鉄の近接時には発振回路
は発振せず又は発振レベルが低下し、アルミニウム等の
非磁性体が近接したときには発振が開始され又は振幅レ
ベルが上昇するので、非磁性体の物品のみを検出するこ
とができるという効果が得られる。Furthermore, in the invention of claim 2 of the present application, when iron comes close, the oscillation circuit does not oscillate or the oscillation level decreases, and when a non-magnetic material such as aluminum comes close, oscillation starts or the amplitude level increases. The effect is that only magnetic articles can be detected.
更に本願の請求項３の発明では、鉄等の磁性体の近接に
伴う発振振幅の低下により磁性体のみを非磁性体と弁別
して検出することができるという効果が得られる。Furthermore, in the invention of claim 3 of the present application, the oscillation amplitude decreases as magnetic materials such as iron come close to each other, so that it is possible to detect only magnetic materials while distinguishing them from non-magnetic materials.
第１図は本発明の近接スイッチの基本的な構成を示すブ
ロック図である。本図において増幅回路１１に正帰還回
路１２が接続されて発振回路１３を構成している。発振
回路１３の出力は前述した従来例と同様に検波回路３に
与えられる。検波回路３はこの出力を検波して振幅に対
応した直流レベルの信号に変換し比較回路５に与える。FIG. 1 is a block diagram showing the basic configuration of a proximity switch of the present invention. In this figure, a positive feedback circuit 12 is connected to an amplifier circuit 11 to form an oscillation circuit 13. The output of the oscillation circuit 13 is given to the detection circuit 3 as in the conventional example described above. The detection circuit 3 detects this output, converts it into a DC level signal corresponding to the amplitude, and supplies it to the comparison circuit 5.
比較回路５は所定の閾値でその出力を弁別するものであ
り、出力回路６を介して物体検知信号を外部に出力する
ことは前述した従来例と同様である。さて本発明では正
帰還回路１２に発振周波数と異なるタンク回路が接続さ
れる。The comparison circuit 5 discriminates its output using a predetermined threshold value, and outputting the object detection signal to the outside via the output circuit 6 is similar to the conventional example described above. Now, in the present invention, a tank circuit having a different oscillation frequency is connected to the positive feedback circuit 12.
第２図は本実施例の発振回路１３を示す回路図である。FIG. 2 is a circuit diagram showing the oscillation circuit 13 of this embodiment.
この３発振回路１３はＬＣ型の発振回路であって、コイ
ルＬ１及びコンデンサＣ１，Ｃ２から成り共振周波数ｆ
、の第１のタンク回ＩＩｔＴｌを有している。このタン
ク回路ＴＩのコイルＬ１のホントエンド端はトランジス
タＴｒｉのベースに接続されている。トランジスタＴｒ
ｉのコレクタは電源端に接続され、そのエミッタには正
帰還回路１２が接続される。本実施例においては正帰還
回路１２は直列接続された抵抗Ｒ１，Ｒ２を有し、その
中点と接地端間には第２のタンク回路Ｔ２が接続される
。第２のタンク回路Ｔ２は検出コイルＬ２とコンデンサ
Ｃ３から構成され、第１のタンク回路Ｔ１の共振周波数
ｆ１よりわずかに高い共振周波数ｆ２を有するものとす
る。コイルＬ２は近接スイッチの前面に設けられ近接す
る物体によってコイルの損失分やサセプタンスが変化す
るように構成される。そしてコイルＬｌには二次側にコ
イルＬ３が接続されコイルＬ３を介して発振出力が検波
回路３に伝えられる。This three-oscillation circuit 13 is an LC type oscillation circuit, and consists of a coil L1 and capacitors C1 and C2, and has a resonance frequency f
, has a first tank time IItTl. The real end of the coil L1 of this tank circuit TI is connected to the base of the transistor Tri. Transistor Tr
The collector of i is connected to the power supply end, and the positive feedback circuit 12 is connected to its emitter. In this embodiment, the positive feedback circuit 12 has resistors R1 and R2 connected in series, and a second tank circuit T2 is connected between the midpoint and the ground terminal. The second tank circuit T2 is composed of a detection coil L2 and a capacitor C3, and has a resonant frequency f2 slightly higher than the resonant frequency f1 of the first tank circuit T1. The coil L2 is provided on the front surface of the proximity switch and is configured such that the loss and susceptance of the coil changes depending on the object that approaches. A coil L3 is connected to the secondary side of the coil Ll, and the oscillation output is transmitted to the detection circuit 3 via the coil L3.
第３図は前述した２つのタンク回路Ｔｌ、Ｔ２のコイル
Ｌｌ、Ｌ２を熱的に同環境となるようにした近接スイッ
チの構成を示す断面図である。本図に示すようにタンク
回路Ｔ１及びＴ２のコイルＬＬ、Ｌ２を夫々図示のよう
に環状の窪みを持つボットコア１４．１５内に実装し、
検出コイルＬ２を近接スイッチの前面に配置する。そし
てケース１６の内部には発振回路１３及び検波回路や比
較回路等信の電子回路部を実装したプリント基板１７を
設ける。そしてその増隙部にはエポキシ樹脂１８等の充
填材を充填して近接スイッチを構成する。こうすれば２
つのコイルを熱的に同環境にすることができるため温度
ドリフト等に対して安定に動作させることができる。FIG. 3 is a sectional view showing the configuration of a proximity switch in which the coils Ll and L2 of the two tank circuits Tl and T2 described above are placed in the same thermal environment. As shown in this figure, the coils LL and L2 of tank circuits T1 and T2 are respectively mounted in a bot core 14.15 having an annular recess as shown,
A detection coil L2 is placed in front of the proximity switch. Inside the case 16 is provided a printed circuit board 17 on which the oscillation circuit 13 and electronic circuit sections such as a detection circuit and a comparison circuit are mounted. Then, the increased gap portion is filled with a filler such as epoxy resin 18 to form a proximity switch. If you do this, 2
Since the two coils can be placed in the same thermal environment, they can operate stably against temperature drift, etc.
次に本実施例の動作について説明する。第４図において
曲ｉＡ、Ｂは２つのタンク回路Ｔｌ、Ｔ２の周波数に対
する振幅レベルの変化を示している。本図に示すように
タンク回路Ｔｌの共振周波数ｆ１を低く、タンク回路Ｔ
２の共振周波数ｆ２をより高くなるように設定する。そ
して発振回路１３の発振周波数ｆ０は回路全体の利得が
最大となる点、即ち２つのタンク回路の振幅特性の交点
である周波数「。で発振する。さてこの図において第２
のりンク回路Ｔ２の検出コイルＬ２に鉄製の物体が近接
したときには検出コイルの損失成分が増加するため、そ
の振幅特性が８１に示すように変化する。Next, the operation of this embodiment will be explained. In FIG. 4, songs iA and B show changes in amplitude level with respect to frequency of two tank circuits Tl and T2. As shown in this figure, the resonance frequency f1 of the tank circuit Tl is lowered, and the tank circuit T
The resonant frequency f2 of 2 is set to be higher. The oscillation frequency f0 of the oscillation circuit 13 oscillates at the point where the gain of the entire circuit is maximum, that is, the frequency "." which is the intersection of the amplitude characteristics of the two tank circuits.
When an iron object approaches the detection coil L2 of the link circuit T2, the loss component of the detection coil increases, and its amplitude characteristic changes as shown at 81.
従ってそのとき発振周波数ｆ０はわずかに上昇しｆｏｌ
となり、正帰還の帰還量が低下するため発振回路１３の
振幅も低下することとなる。ここでこの振幅の低下は第
４図中の曲線Ａ、Ｂと曲線Ａ、Ｂｌの交点の差Ｄ１とし
て示される。さてタンク回路Ｔ２の検出コイルＬ２にア
ルミニウム材料の物体が接近したときには、その振幅特
性は例えばＢから８２に示すように共振周波数ｆ２が高
く、例えば図示のように周波数ｆ□となるように変化す
る。Therefore, at that time, the oscillation frequency f0 increases slightly and fol
Therefore, since the amount of positive feedback decreases, the amplitude of the oscillation circuit 13 also decreases. Here, this decrease in amplitude is shown as a difference D1 between the intersections of curves A and B and curves A and Bl in FIG. Now, when an aluminum material object approaches the detection coil L2 of the tank circuit T2, its amplitude characteristics change from B to 82, for example, from a high resonance frequency f2 to a frequency f□ as shown in the figure. .
従って共振周波数ｆ、はわずかに上昇することとなるが
、このとき共振周波数ｆ、の変化に伴い振幅も同時に低
下することとなる。このときの振幅変化は曲線Ａ、Ｂと
Ａ、Ｂ２との交点の差Ｄ２として表される。従っである
設定距離に鉄及びアルミニウムの物体が近づいたときの
帰還レベルの変化Ｄ１、Ｄ２が同一となるように設定す
ることにより、鉄とアルミニウム類の物体に対して同一
の感度特性を得ることができる。Therefore, the resonant frequency f will rise slightly, but at this time, the amplitude will also decrease as the resonant frequency f changes. The amplitude change at this time is expressed as a difference D2 between the intersections of the curves A and B and A and B2. Therefore, by setting the feedback level changes D1 and D2 to be the same when iron and aluminum objects approach a certain set distance, it is possible to obtain the same sensitivity characteristics for iron and aluminum objects. I can do it.
又前述した実施例ではＬＣ共振回路を用いた発振回路の
正帰還ループに第２のタンク回路を接続してそのコイル
を検出コイルとしているが、第５図に示すように水晶発
振回路の正帰還ループに第２のタンク回路Ｔ２を設けこ
のコイルを検出コイルとするようにしてもよい。第５図
ではトランジスタＴｒ２のベース・コレクタ間に水晶発
振器２０が取付けられてそのコレクタの出力がエミッタ
フォロワ型のトランジスタＴｒ３によって外部に出力さ
れており、このトランジスタＴｒ２のエミッタと接地端
間に第２のタンク回路Ｔ２を持つ正帰還回路１２が設け
られる。この場合にはトランジスタＴｒ２のベース側か
ら見たタンク回路Ｔ２のインピーダンスは近接する物体
によって変化する。この場合には水晶を用いているため
発振周波数はほとんど同一であり、正帰還のタンク回路
の共振周波数及びその物体に対する特性によって発振回
路の振幅が変化する。即ち第６図に示すように、コイル
Ｌ２に物体が近接しないときのタンク回路Ｔ２の振幅特
性を曲ｖＡＥとし、鉄及びアルミニウム類の物体が近接
したときの特性を夫々曲線Ｅｌ、Ｅ２とする。そして鉄
及びアルミニウムの物体が設定距離に近づいたときにこ
れらの振幅の低下を同一になるようにタンク回路を設定
しておくことにより、同一の感度特性を得ることができ
る。Furthermore, in the embodiment described above, the second tank circuit is connected to the positive feedback loop of the oscillation circuit using the LC resonant circuit, and that coil is used as the detection coil, but as shown in FIG. A second tank circuit T2 may be provided in the loop and this coil may be used as a detection coil. In FIG. 5, a crystal oscillator 20 is attached between the base and collector of the transistor Tr2, and the output of the collector is outputted to the outside by an emitter follower type transistor Tr3. A positive feedback circuit 12 having a tank circuit T2 is provided. In this case, the impedance of the tank circuit T2 viewed from the base side of the transistor Tr2 changes depending on the nearby object. In this case, since a crystal is used, the oscillation frequency is almost the same, and the amplitude of the oscillation circuit changes depending on the resonance frequency of the positive feedback tank circuit and its characteristics with respect to the object. That is, as shown in FIG. 6, the amplitude characteristic of the tank circuit T2 when no object approaches the coil L2 is represented by a curve vAE, and the characteristics when an iron or aluminum object approaches are represented by curves El and E2, respectively. The same sensitivity characteristics can be obtained by setting the tank circuit in such a way that these amplitudes decrease the same when the iron and aluminum objects approach the set distance.
次に本願の請求項２の発明について実施例を参照しつつ
説明する。本実施例においても回路構成は前述した第１
実施例のブロック図及び回路図と同一である。本実施例
では第２のタンク回路Ｔ２の共振周波数ｆ、を第１のタ
ンク回路ＴＩの共振周波数ｆ、に対して低くなるように
設定し、通常の状態では発振が開始されないレベルとし
てアルミニウムのみを検出している。第７図（ａｌ、
（ｂ）は物体が近接しない状態での第２のタンク回路の
振幅特性曲ｗＡＦに対し、鉄製の物体が近接した場合の
曲線をＦｌ、アルミニウム類の物体が近接した状態の′
曲線をＦ２として夫々示している。本図に示すように曲
線ＡとＦとが交わる周波数ｆ、の近傍では、発振を開始
していないものとするとアルミニウムの物体の近接に伴
い発振開始レベルｇを越えるため、図示のように曲６Ｉ
Ｆ２と曲線Ａとの交点を発振周波数ｆ０として発振が開
始される。しかし鉄製の物品が近接した場合には曲線Ｆ
ｌに示すように振幅レベルが更に低下するため発振開始
レベル以下となって発振は開始しない。従ってアルミニ
ウムの近接によりアルミニウムの物体が接近したときに
のみ発振が開始されることとなり、この出力に基づいて
アルミニウム等の非磁性体を検出することが可能となる
。Next, the invention of claim 2 of the present application will be explained with reference to embodiments. In this example as well, the circuit configuration is the same as the first one described above.
It is the same as the block diagram and circuit diagram of the embodiment. In this example, the resonant frequency f of the second tank circuit T2 is set to be lower than the resonant frequency f of the first tank circuit TI, and only aluminum is set to a level at which oscillation does not start under normal conditions. Detected. Figure 7 (al,
(b) shows the amplitude characteristic curve wAF of the second tank circuit when no object is nearby, Fl is the curve when a steel object is nearby, and ′ is when an aluminum object is nearby.
The curves are respectively indicated as F2. As shown in the figure, near the frequency f where curves A and F intersect, if oscillation has not started, the oscillation start level g will be exceeded as the aluminum object approaches.
Oscillation is started with the intersection of F2 and curve A as the oscillation frequency f0. However, when iron objects are close together, curve F
Since the amplitude level further decreases as shown in 1, it becomes below the oscillation start level and oscillation does not start. Therefore, oscillation is started only when an aluminum object approaches due to the proximity of aluminum, and it becomes possible to detect non-magnetic materials such as aluminum based on this output.
又この発振回路を常に発振させておき第７図に示すｇを
閾値レベルとすることによりこのレベルを越えたときに
非磁性体を検出するようにしてもよい。Alternatively, the oscillation circuit may be kept in constant oscillation, and by setting g shown in FIG. 7 as a threshold level, a non-magnetic material may be detected when this level is exceeded.
次に本願の請求項３の発明について説明する。Next, the invention of claim 3 of the present application will be explained.
本実施例においても回路構成は前述した第１実施例のブ
ロック図及び回路図と同一であり、前述した実施例と同
様に第２のタンク回路Ｔ２の共振周波数ｆ、を第１のタ
ンク回路ＴＩの共振周波数に対して低くなるように設定
している。そして第７図に示すグラフにおいて比較回路
の閾値を第７図（ａ）。The circuit configuration of this embodiment is also the same as the block diagram and circuit diagram of the first embodiment described above, and similarly to the embodiment described above, the resonance frequency f of the second tank circuit T2 is changed to the resonance frequency f of the second tank circuit T2. It is set to be lower than the resonant frequency of. In the graph shown in FIG. 7, the threshold value of the comparison circuit is shown in FIG. 7(a).
（ｂｌに示すｈのレベルに設定しておくものとする。(It is assumed that the level h shown in bl is set.
こうすれば鉄等の磁性体が接近したときに振幅がこのレ
ベルより低下しアルミニウム等の非磁性体では元の振幅
レベルより大きくなるため、磁性体の金属のみを検出す
ることが可能となる。In this way, when a magnetic material such as iron approaches, the amplitude decreases below this level, and in the case of a non-magnetic material such as aluminum, the amplitude becomes higher than the original level, making it possible to detect only magnetic metals.
第１図は本発明の近接スイッチの基本的な構成を示すブ
ロック図、第２図は発振回路の一実施例を示す回路図、
第３図は近接スイッチの構造を示す断面図、第４図はタ
ンク回路の周波数に対する振幅レベルの変化を示す図、
第５図は本発明の梁側による近接スイッチの周波数に対
する振幅特性を示すグラフ、第８図は従来の近接スイッ
チの一例を示すブロック図である。
３・・−・・検波回路 ５・−・−・・・比較回路
６−・・−＝出力回路 １１−・−・〜・増幅回路
１２−・−・−正帰還回路 １３−・−・・発振
回路 Ｔ １ 、 Ｔ ２−−タンク回路 Ｌ２−
・−検出コイル
特許出願人 立石電機株式会社
代理人 弁理士 岡本官喜（他Ｉ名）
第１図
第３図
第４図
↑１ ｔｏｌＴ２ Ｔ２１ 問、ＩＬ叡第５図
第６図
ｉｏ １＠ｉ艷
第７図（ａ）−
第７図（ｂ）FIG. 1 is a block diagram showing the basic configuration of the proximity switch of the present invention, FIG. 2 is a circuit diagram showing an example of an oscillation circuit,
FIG. 3 is a cross-sectional view showing the structure of the proximity switch, FIG. 4 is a diagram showing changes in amplitude level with respect to frequency of the tank circuit,
FIG. 5 is a graph showing amplitude characteristics with respect to frequency of the beam-side proximity switch of the present invention, and FIG. 8 is a block diagram showing an example of a conventional proximity switch. 3.---Detection circuit 5.---Comparison circuit
6-...-=Output circuit 11----Amplification circuit 12---Positive feedback circuit 13---Oscillation circuit T1, T2--Tank circuit L2-
・-Detection coil patent applicant Tateishi Electric Co., Ltd. agent Patent attorney Kanki Okamoto (and I others) Figure 1 Figure 3 Figure 4 ↑ 1 tolT2 T21 Q, IL E Figure 5 Figure 6 io 1@i Figure 7 (a) - Figure 7 (b)
Claims (3)
振回路の正帰還ループ間に接続され前記発振周波数より
わずかに高い共振周波数ｆ＿２（ｆ＿０＜ｆ＿２）を有
するタンク回路と、前記発振回路の振幅を所定の閾値レ
ベルで弁別する比較回路と、を有し、磁性体及び非磁性
体金属体が同一位置に近接したとき同一の発振レベルが
低下する発振周波数に設定したことを特徴とする高周波
発振型近接スイッチ。(1) An oscillation circuit that oscillates at an oscillation frequency f_0, a tank circuit connected between the positive feedback loop of the oscillation circuit and having a resonant frequency f_2 (f_0<f_2) slightly higher than the oscillation frequency, and an amplitude of the oscillation circuit. a comparison circuit for discriminating at a predetermined threshold level, and the oscillation frequency is set to such an oscillation frequency that the same oscillation level decreases when a magnetic material and a non-magnetic metal material come close to the same position. type proximity switch.
振回路の正帰還ループ間に接続され前記発振周波数より
わずかに低い共振周波数ｆ＿３（ｆ＿０＞ｆ＿３）を有
するタンク回路と、前記発振回路の振幅を所定の閾値レ
ベルで弁別する比較回路と、を有し、前記比較回路は非
磁性体の近接による発振振幅の上昇に基づいて非磁性体
のみを検出するものであることを特徴とする高周波発振
型近接スイッチ。(2) An oscillation circuit that oscillates at an oscillation frequency f_0, a tank circuit connected between the positive feedback loop of the oscillation circuit and having a resonant frequency f_3 (f_0>f_3) slightly lower than the oscillation frequency, and an amplitude of the oscillation circuit. a comparison circuit that discriminates at a predetermined threshold level, the comparison circuit detecting only non-magnetic materials based on an increase in oscillation amplitude due to proximity of the non-magnetic materials. type proximity switch.
振回路の正帰還ループ間に接続され前記発振周波数より
わずかに低い共振周波数ｆ＿３（ｆ＿０＞ｆ＿３）を有
するタンク回路と、前記発振回路の振幅を所定の閾値レ
ベルで弁別する比較回路と、を有し、前記比較回路は磁
性体の近接による発振振幅の低下に基づいて磁性体のみ
を検出するものであることを特徴とする高周波発振型近
接スイッチ。(3) An oscillation circuit that oscillates at an oscillation frequency f_0, a tank circuit connected between the positive feedback loop of the oscillation circuit and having a resonant frequency f_3 (f_0>f_3) slightly lower than the oscillation frequency, and an amplitude of the oscillation circuit. a comparison circuit for discriminating at a predetermined threshold level, the comparison circuit detecting only a magnetic substance based on a decrease in oscillation amplitude due to proximity of the magnetic substance. switch.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1134234A JPH02312316A (en) | 1989-05-26 | 1989-05-26 | High frequency oscillation type proximity switch |
| EP19900110062 EP0399563A3 (en) | 1989-05-26 | 1990-05-28 | High frequency oscillation type proximity switch |
| US07/529,357 US5034704A (en) | 1989-05-26 | 1990-05-29 | High frequency oscillation type proximity switch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1134234A JPH02312316A (en) | 1989-05-26 | 1989-05-26 | High frequency oscillation type proximity switch |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02312316A true JPH02312316A (en) | 1990-12-27 |
Family
ID=15123563
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1134234A Pending JPH02312316A (en) | 1989-05-26 | 1989-05-26 | High frequency oscillation type proximity switch |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US5034704A (en) |
| EP (1) | EP0399563A3 (en) |
| JP (1) | JPH02312316A (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0523563A1 (en) * | 1991-07-15 | 1993-01-20 | Omron Corporation | Proximity switch |
| JPH05110412A (en) * | 1991-10-15 | 1993-04-30 | Omron Corp | Oscillator circuit and high frequency oscillation type proximity switch |
| DE4330140C2 (en) * | 1993-09-07 | 1997-07-17 | Ifm Electronic Gmbh | Inductive proximity switch |
| US5582184A (en) * | 1993-10-13 | 1996-12-10 | Integ Incorporated | Interstitial fluid collection and constituent measurement |
| FR2716979B1 (en) * | 1994-03-04 | 1996-03-29 | Telemecanique | Inductive proximity switch. |
| IL110597A (en) * | 1994-08-09 | 2002-11-10 | Micro Tag Temed Ltd | Method for labeling, verification and/or identifying an object and device for implementing said method |
| US5801530A (en) * | 1995-04-17 | 1998-09-01 | Namco Controls Corporation | Proximity sensor having a non-ferrous metal shield for enhanced sensing range |
| FR2735224B1 (en) * | 1995-06-08 | 1997-07-18 | Silec Liaisons Elec | ELECTROMAGNETIC SENSOR AND METHOD FOR THE SIMULTANEOUS DETERMINATION OF DIFFERENT PARAMETERS OF AN ASSOCIATED TARGET |
| US6476604B1 (en) * | 1999-04-12 | 2002-11-05 | Chartered Semiconductor Manufacturing Ltd. | Method and apparatus for identifying high metal content on a semiconductor surface |
| US6446012B1 (en) * | 1999-06-23 | 2002-09-03 | Bfcs Technology, Inc. | Proximity detector for hard-to-detect materials |
| ITMO20030300A1 (en) * | 2003-11-07 | 2005-05-08 | M D Micro Detectors Spa | INDUCTIVE PROXIMITY SENSOR, IN PARTICULAR TO DETECT THE PRESENCE OF FERROUS AND NON-FERROUS MATERIALS |
| JP4385825B2 (en) * | 2004-03-31 | 2009-12-16 | オムロン株式会社 | Proximity sensor |
| US7511482B2 (en) * | 2005-08-31 | 2009-03-31 | I F M Electronic Gmbh | Inductive proximity switch |
| US8432169B2 (en) * | 2007-09-20 | 2013-04-30 | Panasonic Corporation | Proximity sensor |
| US8258777B2 (en) * | 2009-09-04 | 2012-09-04 | Weihua Chen | Inductive proximity sensor |
| DE102009044820B4 (en) | 2009-12-08 | 2011-09-01 | Turck Holding Gmbh | Self-calibrating proximity switch |
| DE102011016504B4 (en) * | 2011-04-08 | 2013-07-18 | Behr-Hella Thermocontrol Gmbh | Display device for a vehicle component |
| GB2495104A (en) | 2011-09-28 | 2013-04-03 | Oxford Rf Sensors Ltd | Rotor blade sensor |
| EP2674950A1 (en) | 2012-06-11 | 2013-12-18 | Tyco Electronics Nederland B.V. | Contactless connector, contactless connector system, and a manufacturing method for the contactless connector |
| GB2506424B (en) * | 2012-09-28 | 2017-06-07 | Salunda Ltd | Target clearance measurement device |
| US9753068B2 (en) * | 2015-01-14 | 2017-09-05 | Insitu Inc. | Systems and methods for signal quantization |
| WO2017204663A1 (en) | 2016-05-25 | 2017-11-30 | Powerbyproxi Limited | A coil arrangement |
| CN110109183B (en) * | 2019-04-29 | 2024-04-19 | 于凯鸿 | Sensing device for detecting object proximity |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1302191B (en) * | 1960-11-24 | 1971-01-14 | ||
| FR1344681A (en) * | 1963-01-14 | 1963-11-29 | Tateisi Denki Kabushikikaisha | Electrical detector device |
| CH421237A (en) * | 1964-02-05 | 1966-09-30 | Ebauches Sa | Proximity detector |
| DE1915044A1 (en) * | 1969-03-25 | 1970-10-15 | Schaller Dipl Ing Werner | Inductive proximity switch |
| US3896371A (en) * | 1973-12-17 | 1975-07-22 | Allen W Hametta | Metal detector with a resonating circuit being driven by a frequency higher than its natural resonance frequency |
| US3961238A (en) * | 1975-01-22 | 1976-06-01 | Robert F. Gardiner | Selective metal detector circuit having dual tuned resonant circuits |
| FR2320663A1 (en) * | 1975-08-06 | 1977-03-04 | Itt Produits Ind | PROXIMITY DETECTOR OF OBJECTS OF ANY KIND |
| US4263553A (en) * | 1978-05-30 | 1981-04-21 | Cook Kenneth M | Discriminating metal detector with compensation for ground minerals |
| DE3228524C2 (en) * | 1982-07-30 | 1985-05-02 | Siemens AG, 1000 Berlin und 8000 München | Inductive proximity switch |
| JPH069336B2 (en) * | 1987-04-03 | 1994-02-02 | 本田技研工業株式会社 | High frequency oscillation type proximity switch |
| DE3714433C2 (en) * | 1987-04-30 | 1994-04-28 | Turck Werner Kg | Inductive proximity switch |
-
1989
- 1989-05-26 JP JP1134234A patent/JPH02312316A/en active Pending
-
1990
- 1990-05-28 EP EP19900110062 patent/EP0399563A3/en not_active Withdrawn
- 1990-05-29 US US07/529,357 patent/US5034704A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0399563A3 (en) | 1991-07-17 |
| EP0399563A2 (en) | 1990-11-28 |
| US5034704A (en) | 1991-07-23 |
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